1. Technical Field
The present invention relates to a technology for adjusting an image to be displayed by an image display apparatus.
2. Related Art
In image display apparatuses for displaying various images including moving images, image signals are input, and then processed in real-time to be displayed. Therefore, in the past, in image display apparatuses such as projectors, CRTs, or LCDs, it has been general to use RGB (red, green, and blue) signals or YUV (luminance, first chrominance, and second chrominance) signals as the image signal in order to achieve easiness of display and simplification of the process.
Although the hue, brightness, chroma, and so on of the image to be displayed in such image display apparatuses can be adjusted in the sources (e.g., DVD players) of the image signals, in recent years, the image display apparatuses such as projectors are also provided with mechanisms for adjustment. When the user tries to adjust the color, brightness, sharpness, and so on of the image, the user needs to directly adjust the RGB signals, the YUV signals and so on normally processed by the image display apparatus. However, in these signals, if one of the signals is strengthened or weakened, the variation influences other colors, and therefore, it has been difficult to obtain a desired image.
Therefore, in the past, for example in color scanners, it has been performed that the RGB signals of a reference image are once converted into HLS signals to calculate differences from reference colors, and then the color adjustment of the image read therein is performed using the result of the calculation (see, e.g., JP-A-9-18724). The HLS signals are signals compliant to the Munsell color system represented by HLS (hue, lightness, and saturation) as a reference of an object color. As a technology for performing color correction using the HLS signals what is disclosed in JP-A-11-69186 is also known.
However, both of these technologies are intended to correct misalignment included in the image processing system or shift in balance, and therefore, it is not achievable to adjust the image signals processed in real-time to be a desired state and to perform display in the image display apparatus such as a projector, which may handle a moving image. The user only prefer to adjust the color, brightness, sharpness and so on of the image displayed presently according to the preference, but does not prefer to adjust the RGB signals or the YUV signals themselves. In the image display apparatus of the related art, there arises a problem that it is not achievable to meet the request of such a user.